Sunscreen cooling material with radiation cooling and hygroscopic evaporation effect and preparation method and application thereof

Abstract

The application belongs to the technical field of new energy and energy-saving materials, and particularly relates to a sun-proof cooling material with radiation cooling and moisture absorption and volatilization effects, and a preparation method and application thereof. The sun-proof cooling material is prepared by the following steps: adding an organic polymer, a sunscreen agent and inorganic micro-nano particles into an organic solvent to obtain a mixed solution, spraying the mixed solution on a breathable layer I to dry to form a heat dissipation layer, adding a moisture absorbent into a precursor solution prepared from a polymer hydrophilic matrix and deionized water, and freeze-drying the precursor solution to obtain a gel film with moisture absorption function, laminating the heat dissipation layer, the breathable layer I, the gel film and a breathable layer II in sequence to obtain the sun-proof cooling material with the radiation cooling and moisture absorption and volatilization effects. The sun-proof cooling material can reflect most of the sunlight, emit heat outward by emitting mid-far infrared rays, achieve heat dissipation, and realize low-cost and energy-free cooling and sun-proofing by guiding moisture through the breathable layer and cooperating with the heat dissipation layer. The sun-proof cooling material is simple to prepare and can be produced on a large scale.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of new energy and energy-saving materials, and particularly relates to a sunscreen cooling material with radiation cooling and moisture absorption and evaporation effects and a preparation method and application thereof. BACKGROUND

[0002] With the change of global climate, extreme high-temperature weather appears more and more frequently, and people's demand for cooling is also increasing. According to statistics, building energy consumption accounts for 45% of the total energy consumption in China. Buildings absorb solar heat on the surface due to sunlight, causing the temperature to rise and heat the interior air through heat conduction. According to data from the International Institute of Refrigeration, the electricity consumed by air conditioners and refrigerators accounts for about 20% of global electricity consumption. The use of air conditioners, refrigerators and other cooling appliances has increased electricity consumption, and overloading often causes power outages. Therefore, achieving energy-free active cooling is an important goal for energy-saving and carbon-reducing production.

[0003] In addition, strong solar radiation has a great harm to human health, and the number of deaths caused by it is much higher than that of other extreme weather events. At the same time, the southern region is rainy and humid, and the air humidity is high. Compared with the dry and hot weather in the northern region, high temperature and humidity are more detrimental to heat dissipation and more harmful. This is because when people feel hot, the skin will automatically sweat to remove heat through evaporation of sweat, thereby cooling the human body. However, in a humid environment, sweat evaporates slowly, and heat dissipation is also slow. People will sweat all the time, but they will not feel cool, and their body temperature will still be high. High temperature and humidity hinder the evaporation of sweat and are not conducive to heat dissipation, often making people feel hot and weak, and even causing heatstroke.

[0004] Patent CN115323597A discloses a preparation method of soft moisture-absorbing and breathable cotton ammonia fabric. By introducing water-soluble vinylon fibers into the fabric and dissolving them, the fabric has moisture-conducting, breathable and moisture-absorbing capabilities. However, relying solely on the evaporation of moisture to cool down is far from enough to achieve outdoor cooling, and outdoor cooling is still a pressing problem. SUMMARY

[0005] In view of the defects and shortcomings of the prior art, the present application aims to provide a sun-proof cooling material with radiation cooling and moisture absorption and evaporation effects, and a preparation method and application thereof.The prepared sun-proof cooling material can reflect most of sunlight and emit heat outward by emitting mid and far infrared rays, thereby achieving heat dissipation; the sun-proof cooling material has excellent moisture absorption and storage capacity due to the setting of a moisture absorption layer, and moisture is guided through the moisture-permeable layer, and heat is taken away under the effect of water evaporation, thereby achieving synergistic cooling with the heat dissipation layer, realizing low-cost and energy-free cooling and sun-proofing, and being simple to prepare and capable of being produced on a large scale.

[0006] In order to achieve the above-mentioned application purposes, the present application adopts the following technical solutions:

[0007] One of the purposes of the present application is to provide a preparation method of a sun-proof cooling material with radiation cooling and moisture absorption and evaporation effects, which comprises the following steps:

[0008] (1) 5-20 parts by mass of an organic polymer is dissolved in 60-80 parts by mass of an organic solvent, 10-20 parts of a sunscreen agent and 10-30 parts by mass of inorganic micro-nano particles are added and uniformly mixed to obtain a mixed solution;

[0009] (2) 2-5 parts by mass of a high-molecular hydrophilic matrix is stirred with deionized water to form a precursor solution, 5-10 parts by mass of a moisture absorbent is added to the precursor solution, uniformly mixed and then left to remove bubbles, and a gel film with moisture absorption function is obtained by freeze-drying;

[0010] (3) the mixed solution of step (1) is sprayed on one side of the moisture-permeable layer I, and a 50-400 mu m heat dissipation layer with the moisture-permeable layer I as the base is obtained after drying, one side of the gel film is attached to the other side of the moisture-permeable layer I, and the other side of the gel film is attached to the moisture-permeable layer II, and then laminated in the order of the heat dissipation layer, the moisture-permeable layer I, the gel film and the moisture-permeable layer II, with the gel film as the interlayer, to obtain the sun-proof cooling material after lamination.

[0011] Preferably, the organic polymer and the inorganic micro-nano particles in step (1) can reflect most of sunlight and emit heat outward by emitting mid and far infrared rays. More preferably, the coating heat dissipation layer obtained after the mixed solution is sprayed and dried has a reflectivity of not less than 90% in the solar spectrum range (wavelength 300-2500 nm) and an infrared emissivity of not less than 90% in the atmospheric window wavelength range (wavelength 8-13 mu m), and can cool without any energy input, showing great potential in sustainable energy-saving development.

[0012] Preferably, the organic polymer in step (1) is at least one selected from polydimethylsiloxane, polymethyl methacrylate, polyvinylidene fluoride, polyethylene oxide and polylactic acid.

[0013] Preferably, the organic solvent of step (1) is selected from at least one of N-methyl pyrrolidone, N,N-dimethylformamide, toluene, tetrahydrofuran, acetone.

[0014] Preferably, after the organic polymer is added into the organic solvent, the mixture is stirred at 50-80°C for 1-2h to accelerate the dissolution, and the stirring speed is 100-500r / min until the organic polymer is completely dissolved.

[0015] Preferably, the inorganic micro-nanoparticles of step (1) are selected from at least one of titanium dioxide, aluminum oxide, silicon dioxide, barium sulfate, or hollow glass microbeads. More preferably, the particle size of the inorganic micro-nanoparticles is 1nm-1000μm.

[0016] Preferably, the sunscreen of step (1) includes physical sunscreen and chemical sunscreen, and more preferably the sunscreen is selected from one or more of titanium dioxide, zinc oxide, ethylhexyl methoxy cinnamate, octocrylene, methyl anthranilate, oxybenzone, avobenzone, homosalate. More preferably, the sunscreen can reflect or absorb ultraviolet light, further improve the sunscreen performance, reduce the damage of ultraviolet light to human skin and object surface, and achieve excellent sunlight protection effect in the full wave band.

[0017] More preferably, when the sunscreen is a chemical sunscreen and can be dissolved in the organic solvent, the sunscreen is first added and dissolved and mixed uniformly, and then the inorganic micro-nanoparticles are added and mixed uniformly.

[0018] More preferably, after the sunscreen of step (1) is added, the mixture is stirred at room temperature for 1-2h to make it mixed uniformly, and the stirring speed is 100-300r / min; after the inorganic micro-nanoparticles are added, the mixture is stirred at room temperature for 2-6h to make it mixed uniformly, and the stirring speed is 100-500r / min.

[0019] Preferably, the high-molecular hydrophilic matrix of step (2) is selected from at least one of carbomer, hydroxypropyl methyl cellulose, methyl cellulose, sodium carboxymethyl cellulose, and chitosan. More preferably, the high-molecular hydrophilic matrix is stirred with deionized water for 10-30min until a uniform and transparent 4-8wt% precursor solution is formed, and the stirring speed is preferably 100-500r / min.

[0020] Preferably, the hygroscopic agent of step (2) is selected from at least one of lithium chloride, calcium chloride, magnesium chloride, cellulose, polyvinyl alcohol, sodium alginate. More preferably, the hygroscopic agent has excellent hygroscopic capacity, can increase the air and moisture permeability, and further reduce the body surface temperature. More preferably, the hygroscopic agent is slowly added to the precursor solution, stirred and mixed uniformly, the stirring speed is preferably 100-500 r / min, after vortex is generated, it is quickly poured into the mold, and is placed at room temperature for 15-30 minutes to remove bubbles, and waits for solvent evaporation to form a film; then, the mold is further reduced in moisture by freeze-drying, the mold is placed into a freeze-drying machine, the cold trap temperature is adjusted to -60℃, pre-freezing is performed for 2-5 h, the drying temperature is set to 0-40℃ under vacuum conditions, and after drying for 8-12 hours, the gel film with hygroscopic function is obtained by peeling off from the mold.

[0021] Preferably, the thickness of the gel film of step (2) is 50-300 μm. Under this thickness, the sun protection and cooling material has more excellent hygroscopic cooling effect.

[0022] Preferably, the air-permeable layer I and the air-permeable layer II of step (3) are air-permeable fabrics, which can guide moisture, and more preferably the air-permeable fabrics include at least one of cotton fabric, linen fabric, non-woven fabric, cellulose-based fabric, and chemical fabric. The thicknesses of the air-permeable layer I and the air-permeable layer II are 100-500 μm, respectively.

[0023] Preferably, the spraying process in step (3) is spraying using a spray gun, the driving pressure is 0.1-0.2 bar, the nozzle size is 1-2.5 mm, the spraying flow rate is 500-800 mL / min, the spraying distance is 20-40 cm, the spraying time is 5-10 s, and the spraying area is 40*40 cm. -1 Preferably, the spraying process in step (3) is spraying using a spray gun, the driving pressure is 0.1-0.2 bar, the nozzle size is 1-2.5 mm, the spraying flow rate is 500-800 mL / min, the spraying distance is 20-40 cm, the spraying time is 5-10 s, and the spraying area is 40*40 cm.

[0024] Preferably, after the mixed solution is sprayed on one side of the air-permeable layer I in step (3), it is placed in an oven at 60-100℃ for 1-2 h, and is taken out after drying, to obtain the heat dissipation layer with the air-permeable layer as the substrate.

[0025] Preferably, the laminating process in step (3) is an adhesive production process, and the adhesive selected for laminating is selected from at least one of polyurethane resin, vinyl acetate resin, acrylic resin, polyamide resin, and epoxy resin. The adhesive is coated on the laminated surface of the air-permeable layer I and II, is dried at 50-80℃ for 1-2 minutes, is integrated with the corresponding air-permeable layer, to obtain the adhesive-coated air-permeable layer, and then the gel film and the adhesive-coated air-permeable layer are attached and are hot-pressed at a temperature of 50-100℃ and a pressure of 196-394 kPa for 50-120 s, to be pressed into shape, to obtain the sun protection and cooling material.

[0026] Preferably, the thickness of the sun-proof cooling material is 300-1700 mu m. By adopting the technical scheme, the moisture absorption and cooling effect of the sun-proof cooling material is more excellent.

[0027] The second object of the present application is to provide a sun-proof cooling material with radiation cooling and moisture absorption and evaporation effects prepared by any of the above preparation methods.

[0028] The third object of the present application is to provide an application of the sun-proof cooling material with radiation cooling and moisture absorption and evaporation effects prepared by any of the above preparation methods in the field of thermal management. The field of thermal management includes the fields of surfaces requiring cooling such as automobiles, daily chemicals, clothing, etc.

[0029] Compared with the prior art, the present application has the following beneficial effects: the prepared sun-proof cooling material can reflect most of the sunlight and emit heat outward by emitting mid-infrared rays, thereby achieving heat dissipation. Meanwhile, the sun-proof cooling material has excellent moisture absorption and storage capacity by setting the moisture absorption layer gel film, and moisture is guided through the moisture-permeable layer, and heat is taken away under the action of water evaporation, thereby achieving synergistic cooling with the heat dissipation layer, realizing low-cost and energy-saving cooling and sun-proofing, and being simple to prepare and capable of being mass-produced. The sun-proof cooling material has the following advantages: 1. active cooling and ultraviolet protection; 2. good moisture absorption and permeability; 3. energy saving, low cost and wide application range; 4. good hydrophobicity and dirt resistance; and therefore has a wide application prospect. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 It is a flowchart of the preparation method of the sun-proof cooling material.

[0031] Figure 2 It is a structural diagram of the sun-proof cooling material. In the figure: 1, heat dissipation layer; 2, moisture-permeable layer I; 3, gel film; 4, moisture-permeable layer II. DETAILED DESCRIPTION

[0032] The technical scheme of the present application will be further described below by means of specific embodiments and in combination with the drawings.

[0033] Example 1

[0034] (1) 10 parts by mass (1 part by mass is 0.1 g) of polymethyl methacrylate was dissolved in 65 parts by mass of N,N-dimethylformamide, preferably stirred at 50 DEG C for 1 h to accelerate dissolution, and the stirring speed was 300 r / min until the organic polymer was completely dissolved; then 15 parts of Oliklin was added and stirred at room temperature at 300 r / min for 2 h until complete dissolution, and then 15 parts by mass of 50 mu m silicon dioxide was added and stirred at room temperature at 500 r / min for 4 h, and the mixture was uniformly mixed to obtain a mixed solution;

[0035] (2) 4 parts by mass of methyl cellulose and deionized water were stirred for 20 minutes until a uniform and transparent 8 wt% precursor solution was formed at a stirring speed of 300 r / min. Then, 8 parts by mass of lithium chloride were slowly added to the precursor solution. After a vortex was generated, the solution was quickly poured into a mold and allowed to stand at room temperature for 15 minutes. Then, the mold was placed in a freeze dryer, the cold trap temperature was adjusted to -60°C, and after pre-freezing for 2 hours, the drying temperature was set to 10°C under vacuum conditions. After drying for 12 hours, the gel film with a thickness of 200 μm and a hygroscopic function was obtained by peeling it off from the mold.

[0036] (3) Spray the mixture of (1) on one side of 500 μm linen cloth I with a driving pressure of 0.1 bar, a nozzle size of 1 mm, and a spray flow rate of 500 mL min -1 The spraying distance was 20 cm, the spraying time was 5 seconds, and the spraying area was 40 x 40 cm. The film was placed in an oven at 100°C for 1 hour and dried. This resulted in a 200 μm heat dissipation layer based on linen. One side of the gel film was then laminated to the other side of linen I, and the other side of the gel film was then laminated to linen II. The gel film served as the interlayer, resulting in a sunscreen and cooling material. The adhesive used for lamination was polyurethane resin. Lamination was performed by hot pressing at 80°C and 200 kPa for 80 seconds, followed by compression molding.

[0037] The sunscreen and cooling material obtained in this embodiment has a reflectivity of 92% in the solar spectrum range (wavelength 300 to 2500 nm), an infrared emissivity of not less than 95% in the atmospheric window wavelength range (wavelength 8 to 13 μm), and a water absorption rate of 0.9 g under 30% humidity conditions. -1 , the maximum tensile strength is 200N / 5cm, and the maximum elongation at break is 10%.

[0038] Example 2

[0039] (1) dissolving 15 parts by mass (1 part by mass is 0.1 g) of polyvinylidene fluoride in 60 parts by mass of N-methylpyrrolidone, preferably stirring at 80° C. for 2 h, accelerating dissolution at a stirring speed of 400 r / min, until the organic polymer is completely dissolved; then adding 20 parts of zinc oxide and stirring at 300 r / min at room temperature for 2 h, then adding 19 parts by mass of 500 nm barium sulfate and stirring at 300 r / min at room temperature for 6 h, and mixing uniformly to obtain a mixed solution;

[0040] (2) 5 parts by mass of Carbomer 940 was stirred with deionized water for 15 min until a uniform transparent 5 wt% precursor solution was formed, the stirring speed was 400 r / min, then 5 parts by mass of calcium chloride was slowly added into the precursor solution, after vortex was generated, it was quickly poured into the mold, and placed at room temperature for 30 min; then, the mold was placed into a freeze dryer, the cold trap temperature was adjusted to -60°C, pre-frozen for 3 h, then the drying temperature was set to 30°C under vacuum condition, dried for 8 h, and then peeled off from the mold to obtain a 300 μm thick gel film with moisture absorption function;

[0041] (3) The mixed solution of (1) was sprayed on one side of the 200 μm cellulose-based fabric I, the driving pressure was 0.1 bar, the nozzle size was 2 mm, the spraying flow rate was 600 mL min -1 , the spraying distance was 30 cm, the spraying time was 6 s, the spraying area was 40*40 cm, and it was placed in an oven at 60°C for 2 h, then taken out after drying, to obtain a 100 μm heat dissipation layer based on cellulose-based fabric, then one side of the gel film was attached to the other side of the cellulose-based fabric I, and the other side of the gel film was attached to the cellulose-based fabric II, and then laminated, i.e. the gel film as a sandwich, to obtain a sun protection and cooling material. The adhesive selected for lamination was vinyl acetate resin. Lamination was performed by hot pressing at a temperature of 100°C and a pressure of 268 kPa for 100 s to form a press.

[0042] The sun protection and cooling material obtained in this example had a reflectivity of 95% in the solar spectrum range (wavelength 300 to 2500 nm), an infrared emissivity of 90% in the atmospheric window wavelength range (wavelength 8 to 13 μm), a water absorption rate of 0.85 g g-1 under 30% humidity conditions, a maximum tensile breaking strength of 80 N / 5 cm, and a maximum elongation at break of 30%.

[0043] Example 3

[0044] (1) 20 parts by mass (1 part by mass is 0.1 g) of polydimethylsiloxane was dissolved in 70 parts by mass of N-methylpyrrolidone, preferably stirred at 60°C for 2 h to accelerate dissolution, the stirring speed was 400 r / min, until the organic polymer was completely dissolved; then 20 parts of methoxycinnamic acid ethylhexyl ester was added and stirred at room temperature at 200 r / min for 2 h until completely dissolved, then 30 parts by mass of 100 μm hollow glass microbeads was added and stirred at room temperature at 400 r / min for 6 h, after mixing uniformly, a mixed solution was obtained;

[0045] (2) 5 parts by mass of methyl cellulose was stirred with deionized water for 15 min until a uniform transparent 7 wt% precursor solution was formed, the stirring speed was 500 r / min, then 8 parts by mass of magnesium chloride was slowly added to the precursor solution, and after vortex was generated, it was quickly poured into a mold, and was placed at room temperature for 30 min; then, the mold was placed in a freeze dryer, the cold trap temperature was adjusted to -60°C, and after pre-freezing for 5 h, the drying temperature was set to 20°C under vacuum conditions, and after drying for 12 h, the gel film with a thickness of 100 pm with moisture absorption function was peeled off from the mold;

[0046] (3) The mixed solution of (1) was sprayed on one side of 250 pm cotton cloth I, the driving pressure was 0.2 bar, the nozzle size was 1 mm, the spraying flow rate was 800 mL min -1 , the spraying distance was 40 cm, the spraying time was 5 s, the spraying area was 40*40 cm, and was placed in an oven at 70°C for 2 h, then was taken out after drying, to obtain a 400 pm heat dissipation layer based on cotton cloth, then one side of the gel film was attached to the other side of cotton cloth I, and the other side of the gel film was attached to cotton cloth II, and then was laminated, i.e. the gel film was used as a sandwich layer, and after lamination, a sun protection and cooling material was obtained. The adhesive selected during lamination was acrylic resin. Lamination was performed by hot pressing at a temperature of 70°C and a pressure of 300 kPa for 80 s, and was pressed into shape.

[0047] The sun protection and cooling material obtained in this example had a reflectivity of 97% in the solar spectrum range (wavelength 300 to 2500 nm), an infrared emissivity of 93% in the atmospheric window wavelength range (wavelength 8 to 13 pm), a water absorption rate of 0.96 g g-1 under 30% humidity conditions, a maximum tensile breaking strength of 100 N / 5 cm, and a maximum elongation at break of 10%.

[0048] Example 4

[0049] (1) 15 parts by mass (1 part by mass is 0.1 g) of polyethylene oxide was dissolved in 65 parts by mass of toluene, preferably stirred at 50°C for 2 h to accelerate dissolution, the stirring speed was 200 r / min, until the organic polymer was completely dissolved; then 20 parts of titanium dioxide was added and stirred at 300 r / min at room temperature for 1 h, then 25 parts by mass of 100 nm aluminum trioxide was added and stirred at 500 r / min at room temperature for 2 h, after mixing uniformly, a mixed solution was obtained;

[0050] (2) 5 parts by mass of sodium carboxymethyl cellulose and deionized water were stirred for 30 minutes until a uniform and transparent 8 wt% precursor solution was formed at a stirring speed of 300 r / min. Then, 10 parts by mass of sodium alginate were slowly added to the precursor solution. After a vortex was generated, the solution was quickly poured into a mold and allowed to stand at room temperature for 30 minutes. Then, the mold was placed in a freeze dryer, the cold trap temperature was adjusted to -60°C, and after pre-freezing for 4 hours, the drying temperature was set to 40°C under vacuum conditions. After drying for 8 hours, the gel film with a thickness of 50 μm and a hygroscopic function was obtained by peeling it off from the mold.

[0051] (3) Spray the mixture of (1) onto one side of 350 μm non-woven fabric I with a driving pressure of 0.1 bar, a nozzle size of 1.5 mm, and a spray flow rate of 500 mL min -1 The spraying distance was 40 cm, the spraying time was 10 seconds, and the spraying area was 40 x 40 cm. The film was placed in an 80°C oven for 1 hour and dried. This resulted in a 50 μm heat dissipation layer based on the non-woven fabric. One side of the gel film was then bonded to the other side of non-woven fabric I, and the other side of the gel film was bonded to non-woven fabric II before lamination. The gel film served as an interlayer, resulting in a sunscreen and cooling material. The adhesive used for lamination was polyamide resin. Lamination was performed by hot pressing at 60°C and 300 kPa for 60 seconds, followed by compression molding.

[0052] The sunscreen and cooling material obtained in this embodiment has a reflectivity of 90% in the solar spectrum range (wavelength 300 to 2500 nm), an infrared emissivity of 95% in the atmospheric window wavelength range (wavelength 8 to 13 μm), and a water absorption rate of 0.8 g under 30% humidity conditions. -1 The maximum tensile strength at break is 120N / 5cm, and the maximum elongation at break is 56%.

[0053] Example 5

[0054] (1) 20 parts by mass (1 part by mass is 0.1 g) of polylactic acid are dissolved in 60 parts by mass of tetrahydrofuran, preferably stirred at 50° C. for 1 hour, dissolution is accelerated, and the stirring speed is 100 r / min until the organic polymer is completely dissolved; then 20 parts of ethylhexyl methoxycinnamate are added and stirred at 300 r / min at room temperature for 2 hours until it is completely dissolved, and then 10 parts by mass of 50 μm silica are added and stirred at 400 r / min at room temperature for 5 hours. After mixing evenly, a mixed solution is obtained;

[0055] (2) 4 parts by mass of chitosan and deionized water were stirred for 30 minutes until a uniform and transparent 6 wt% precursor solution was formed at a stirring speed of 300 r / min. Then, 7 parts by mass of cellulose were slowly added to the precursor solution. After a vortex was generated, the solution was quickly poured into a mold and allowed to stand at room temperature for 15 minutes. Then, the mold was placed in a freeze dryer, the cold trap temperature was adjusted to -60°C, and after pre-freezing for 2 hours, the drying temperature was set to 0°C under vacuum conditions. After drying for 10 hours, the gel film with a thickness of 150 μm and a hygroscopic function was obtained by peeling it off from the mold.

[0056] (3) Spray the mixture of (1) on one side of a 200 μm synthetic fiber cloth I with a driving pressure of 0.2 bar, a nozzle size of 2 mm, and a spray flow rate of 700 mL min -1 The spraying distance was 40 cm, the spraying time was 5 seconds, and the spraying area was 40 x 40 cm. The film was placed in a 90°C oven for 1 hour and dried. This resulted in a 200 μm heat dissipation layer based on chemical fiber cloth. One side of the gel film was then bonded to the other side of chemical fiber cloth I, and the other side of the gel film was bonded to chemical fiber cloth II before lamination. The gel film served as the interlayer, resulting in a sunscreen and cooling material. The adhesive used for lamination was epoxy resin. Lamination was performed by hot pressing at 50°C and 200 kPa for 60 seconds, followed by compression molding.

[0057] The sunscreen and cooling material obtained in this embodiment has a reflectivity of 95% in the solar spectrum range (wavelength 300 to 2500 nm), an infrared emissivity of 90% in the atmospheric window wavelength range (wavelength 8 to 13 μm), a water absorption rate of 0.75 g g-1 under 30% humidity conditions, a maximum tensile strength of 70 N / 5 cm, and a maximum elongation at break of 40%.

[0058] Table 1 Comparison of the effects of the embodiments and comparative examples

[0059]

[0060] Table 1 shows the temperature comparison of Examples 1-5 and the comparative example. The naked arm is used as the comparative example. The average temperature is 38℃ and the average solar irradiance is 800W / m 2 As can be seen from Table 1, the temperatures of Examples 1-5 are all 3-4°C lower than the thermal imaging temperature of the control example. This indicates that the sunshade, sunscreen, cooling, and hygroscopic material of the present invention can effectively and actively lower the temperature and meet outdoor cooling needs.

[0061] The above-described embodiments are part, but not all, of the embodiments of the present application, and do not limit the present application in any form. The present application is not limited to the above-described embodiments, and various changes can be made according to the purpose of the present application. Any modification, supplement, and equivalent replacement, etc. made within the principle range of the present application should be included in the protection scope of the present application.

Claims

1. A method for preparing a sunscreen and cooling material with radiation cooling and moisture absorption and volatilization effects, characterized in that: The method comprises the following steps: (1) dissolving 5 to 20 parts by mass of an organic polymer in 60 to 80 parts by mass of an organic solvent, adding 10 to 20 parts by mass of a sunscreen and 10 to 30 parts by mass of inorganic micro-nanoparticles and mixing them uniformly to obtain a mixed solution; (2) 2-5 parts by weight of a polymer hydrophilic matrix and deionized water are stirred to form a precursor solution, and then 5-10 parts by weight of a hygroscopic agent is added to the precursor solution, mixed, and then allowed to stand to remove bubbles, and freeze-dried to obtain a gel film with a hygroscopic function; wherein, the polymer hydrophilic matrix and deionized water are stirred for 10-30 minutes until a uniform and transparent 4-8wt% precursor solution is formed, and the stirring speed is 100-500r / min; the hygroscopic agent is slowly added to the precursor solution, stirred and mixed at 100-500r / min, and after a vortex is generated, it is quickly poured into a mold and allowed to stand at room temperature for 15-30 minutes; then, the mold is placed in a freeze dryer, the cold trap temperature is adjusted to -60°C, and after pre-freezing for 2-5 hours, the drying temperature is set to 0-40°C under vacuum conditions, and after drying for 8-12 hours, it is peeled off from the mold to obtain a gel film with a hygroscopic function; (3) The mixed liquid is sprayed on one side of the breathable layer I and dried, and then one side of the gel film is attached to the other side of the breathable layer I, and the other side of the gel film is attached to the breathable layer II and laminated to obtain a sunscreen and cooling material.

2. The method for preparing a sunscreen and cooling material having radiant cooling and moisture absorption and volatilization effects according to claim 1, characterized in that: The organic polymer of step (1) is selected from at least one of polydimethylsiloxane, polymethyl methacrylate, polyvinylidene fluoride, polyethylene oxide, and polylactic acid; the organic solvent is selected from at least one of N-methylpyrrolidone, N,N-dimethylformamide, toluene, tetrahydrofuran, and acetone; the inorganic micro-nanoparticles are selected from at least one of titanium dioxide, aluminum oxide, silicon dioxide, barium sulfate, or hollow glass microspheres; and the sunscreen is selected from at least one of titanium dioxide, zinc oxide, ethylhexyl methoxycinnamate, octocryl, methyl anthranilate, oxybenzone, octicrine, and trimethylcyclohexyl salicylate.

3. The method for preparing a sunscreen and cooling material having radiant cooling and moisture absorption and volatilization effects according to claim 2, characterized in that: The particle size of the inorganic micro-nano particles is 1 nm-1000 μm.

4. The method for preparing a sunscreen and cooling material having radiant cooling and moisture absorption and volatilization effects according to claim 1, characterized in that: The polymer hydrophilic matrix of step (2) is selected from at least one of carbomer, hydroxypropyl methylcellulose, methylcellulose, sodium carboxymethylcellulose, and chitosan; the hygroscopic agent is selected from at least one of lithium chloride, calcium chloride, magnesium chloride, cellulose, polyvinyl alcohol, and sodium alginate.

5. The method for preparing a sunscreen and cooling material having radiant cooling and moisture absorption and volatilization effects according to claim 1, characterized in that: The gel film thickness of step (2) is 50-300 μm.

6. The method for preparing a sunscreen and cooling material having radiant cooling and moisture absorption and volatilization effects according to claim 1, characterized in that: In step (3), the air-permeable layer I and the air-permeable layer II are made of breathable fabrics, and the thickness of the air-permeable layer I and the air-permeable layer II are respectively 100-500 μm; the thickness of the sun-proof and cooling material is 300-1700 μm.

7. A sunscreen and cooling material having radiative cooling and hygroscopic volatilization effects, prepared by the preparation method according to any one of claims 1 to 6.

8. Application of the sun-proof and cooling material with radiative cooling and hygroscopic volatilization effects as claimed in claim 7 in the field of thermal management.

Images